Used Claude to figure out how to add anaglyph 3D to videos:

ffmpeg -i input.mp4 -vf "
split[left][right];
[right]crop=iw-10:ih:10:0,pad=iw+10:ih:0:0[right_shifted];
[left]colorchannelmixer=rr=1:rg=0:rb=0:ra=0:gr=0:gg=0:gb=0:ga=0:br=0:bg=0:bb=0:ba=0[red];
[right_shifted]colorchannelmixer=rr=0:rg=0:rb=0:ra=0:gr=0:gg=1:gb=0:ga=0:br=0:bg=0:bb=1:ba=0[cyan];
[red][cyan]blend=all_mode=addition
" output_3d.mp4